linux-kernel - [PATCH] panic: call panic handlers before kmsg

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Date:	Thu, 18 Jul 2013 16:03:12 -0700
From:	Kees Cook <keescook@...omium.org>
To:	linux-kernel@...r.kernel.org
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	Anton Vorontsov <anton@...msg.org>,
	Colin Cross <ccross@...roid.com>,
	Tony Luck <tony.luck@...el.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Vikram Mulukutla <markivx@...eaurora.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Rusty Russell <rusty@...tcorp.com.au>
Subject: [PATCH] panic: call panic handlers before kmsg_dump

Since the panic handlers may produce additional information (via printk)
for the kernel log, it should be reported as part of the panic output
saved by kmsg_dump(). Without this re-ordering, nothing that adds
information to a panic will show up in pstore's view when kmsg_dump
runs, and is therefore not visible to crash reporting tools that examine
pstore output.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 kernel/panic.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/kernel/panic.c b/kernel/panic.c
index 8018646..b6c482c 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -123,10 +123,14 @@ void panic(const char *fmt, ...)
 	 */
 	smp_send_stop();
 
-	kmsg_dump(KMSG_DUMP_PANIC);
-
+	/*
+	 * Run any panic handlers, including those that might need to
+	 * add information to the kmsg dump output.
+	 */
 	atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
 
+	kmsg_dump(KMSG_DUMP_PANIC);
+
 	bust_spinlocks(0);
 
 	if (!panic_blink)
-- 
1.7.9.5


-- 
Kees Cook
Chrome OS Security
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